判斷成績是否為NULL

IS NULL

判斷值是否為NULL


學號 成績
S0001 56
S0001 73
S0002 92
S0002 63
S0003 92
S0003 70
S0004 75
S0004 88
S0004 68
S0005 NULL

SELECT *
from  xx
where 成績 IS NULL


不可用    成績 = NULL